Powder coating compositions containing polymer of ethylenically unsaturated glycidyl esters dicarboxylic acids and flow control agents

ABSTRACT

POWDER COATING COMPOSITIONS ARE DISCLOSED. IN GENERAL, INDIVIDUAL POWDER COATING COMPOSITIONS ARE A MIXTURE OF THE FOLLOWING MATERIALS. A COPOLYMER OF GLYCIDYL METHACRYLATE AND AN ETHYLENICALLY UNSATURATED COMPOUND IS FORMED IN SUCH PROPORTIONS AS TO OBTAIN A COPOLYMER WITH A GLASS TRANSITION TEMPERATURE IN THE RANGE OF 40* C. TO 90*C. AND A MOLECULAR WEIGHT ($N) IN THE RANGE OF 2500 TO 8500. THE GLYCIDYL METHACRYLATE IS PRESENT IN THE COPOLYMER FROM AT LEAST ABOUT 8% BY WEIGHT TO NO MORE THAN ABOUT 25% BY WEIGHT. ANOTHER MATERIAL OF THE COATING COMPOSITION IS A SATRUATED, STRAIGHT CHAIN, ALIPHATIC DICARBOXYLIC ACID CONTAINING 4 TO 20 CARBON ATOMS PER MOLECULE IN THE AMOUNT OF 0.8 TO 1.1 CARBOXYLIC GROUPS FOR EACH EPOXY GROUP IN THE COPOLYMER. A THIRD MATERIAL UTILIZED IN FORMING THE POWDER COATING MIXTURE IS A FLOW CONTROL AGENT WHICH FORMS AT LEAST 0.05% BY WEIGHT OF THE MIXTURE. THE FLOW CONTROL AGENT IS A POLYMER HAVING A MOLECULAR WEIGHT ($N) OF AT LEAST 1000. THE FLOW CONTROL AGENT ALSO HAS, AT THE BAKING TEMPERATURE OF THE POWDER COATING COMPOSITION, A LOWER SURFACE TENSION THAN THE SURFACE TENSION OF THE COPOLYMER.

United States Patent 3,752,870 POWDER COATING COMPOSITIONS CONTAININGPOLYMER OF ETHYLENICALLY UNSATU- RATED GLYCIDYL ESTERS, DICARBOXYLICACIDS, AND FLOW CONTROL AGENTS Santokh S. Labana, Dearborn Heights,Mich., assignor to Ford Motor Company, Dearhorn, Mich. No Drawing. FiledAug. 16, 1971, Ser. No. 172,236 Int. Cl. C08g 45/04 US. Cl. 260-836 33Claims ABSTRACT OF THE DISCLOSURE Powder coating compositions aredisclosed. In general, individual powder coating compositions are amixture of the following materials. A copolymer of glycidyl methacrylateand an ethylenically unsaturated compound is formed in such proportionsas to obtain a copolymer with a glass transition temperature in therange of 40 C. to 90 C. and a molecular weight (IL) in the range of 2500to 8500. The glycidyl methacrylate is present in the copolymer from atleast about 8% by weight to no more than about 25% by weight. Anothermaterial of the coating composition is a saturated, straight chain,aliphatic, dicarboxylic acid containing 4 to 20 carbon atoms permolecule in the amount of 0.8 to'1.1 carboxylic groups for each epoxygroup in the copolymer. A third material utilized in forming the powdercoating mixture is a flow control agent which forms at least 0.05% byweight of the mixture. The flow control agent is a polymer having amolecular weight (M,,) of at least 1000. The flow control agent alsohas, at the baking temperature of the powder coating composition, alower surface tension than the surface tension of the copolymer.

BACKGROUND OF THE INVENTION Powder coating compositions for use in thepainting of surfaces are extremely desirable. Such coating compositionsare desirable because they eliminate the solvents utilized in liquidpaint systems as, for example, the paint system shown in US. Patent2,857,354, issued Oct. 21, 1958. A powder coating paint composition iscurable by heat in a manner that little, if any, volatile material isgiven off to the surrounding environment. This, of course, issubstantially different from a liquid paint system as the liquid paintvehicle must be volatilized during the drying of the paint.Volatilization of the liquid vehicle, of course, carries such vaporizedmaterial into the surrounding ambient. 1

This invention is directed to powder coating compositions which aresuitable for finishing surfaces of articles with a protective anddecorative coating. The coatings produced by the compositions of thisinvention are comparable on all terms with the coating produced by theprior are liquid paint systems. The liquid paint system disclosed in US.Patent 2,857,354 is apparently similar but, in reality, substantiallydifferent than the powder coating compositions of this invention. A fulldiscussion of these differences is set forth in the last portion of thisspecification.

SUMMARY OF THE INVENTION This invention is directed to powder coatingcompositions and, more particularly, to powder coating compositionswhich are curable by heat. A powder coating composition formed inaccordance with the teachings of this invention comprises an intimatemixture of several materials. A first material of the mixture is acopolymer of glycidyl methacrylate and an ethylenically unsaturatedcompound in such proportions as to obtain a copolymer 3,752,870 PatentedAug. 14, 1973 with a glass transition temperature in the range of 40 C.to 90 C. and with a molecular weight (IL) in the range of 2500 to 8500.The glycidyl methacrylate is present in the copolymer from at leastabout 8% by weight to no more than about 25 by weight. Another materialof the mixture is a saturated, straight chain, aliphatic, dicarboxylicacid containing 4 to 20 carbon atoms per molecule. The acid is presentin the mixture in the amount of 0.8 to 1.1 carboxylic groups per eachepoxy group in the copolymer. Another material of the mixture is a flowcontrol agent which forms at least 0.05% by weight of the mixture. Thisflow control agent is a polymer having a molecular weight (17 of atleast 1000. The flow control agent also has, at the baking temperatureof the powder coating composition, a lower surface tension than thesurface tension of the copolymer.

In greater detail, the powder coating composition formed in accordancewith the teachings of this invention includes a small weight percent ofa catalyst which produces a gel time for the powder coating compositiongreater than 1 minute at the baking temperature of the composition. Thecoating composition may also use therein a pigment which forms fromabout 6% by weight to about 35% by weight of the total mixture dependingon the pigment selected. The powder coating composition may also includea small weight percentage of an antistatic agent.

The preferred ranges for individual contents of the materials for thepowder coating compositions described above is as follows. The glycidylmethacrylate which forms a portion of the copolymer in the mixtureshould be present in the copolymer in the range of at least 8% by weightto no more than 25% by weight. A desirable range of glycidylmethacrylate in the copolymer is at least 12% by weight to no more than18% by weight with the most desirable copolymer containing approximately15% by weight of the glycidyl methacrylate. Also, the preferred glasstransition temperature for the copolymer is in the range of 50 C. to 80C. with a molecular weight (M,,) in the range of 3000 to 6500. The mostdesirable glass transition temperature for the copolymer is 60 C. to C.with a molecular weight (IL) in the range of 3000 to 4000.

With respect to the saturated, straight chain, aliphatic, dicarboxylicacids used in the powder coating mixture as the cross linking agent, apreferred range of such acids includes the acids having 5 to 13 carbonatoms. The desirable acids are adipic acid, pimelic acid, suberic acid,azelaic acid, sebacic acid, undecandioic acid and brassylic acid, withadipic acid and azelaic acid being the most desirable.

With respect to the flow control agents used in the powder coatingmixture, an individual agent selected for a mixture may be an acrylicpolymer having a glass transition temperature below the glass transitiontemperature of the mixtures copolymer. Preferred acrylic polymers whichmay be used for the flow control agent are polylauryl acrylate,polybutyl acrylate, poly(2-ethylhexyl acrylate, polylauryl methacrylateand polyisodecyl methacrylate.

The flow control agent may also be a fluorinated polymer having asurface tension, at the baking temperature of the powder, lower thanthat of the copolymer utilized in the mixture. Preferred flow controlagents, if the agent is a fluorinated polymer, are esters ofpolyethyleneglycol or polypropyleneglyool and fluorinated fatty acids.For example, an ester of polyethyleneglycol of molecular weight of over2500 and perfluoro octanoic acid is useful as a flow control polymer.

In addition to the glycidyl methacrylate monomer used in all copolymerforming mixtures, other monomers which may be used are methylmethacrylate, butyl methacrylate, butyl acrylate, ethyl acrylate,Z-ethylhexyl acrylate, styrene, alpha methyl styrene, acrylonitrile andmethacrylonitrile. The glycidyl methacrylate and the ethylenicallyunsaturated monomers are mixed and reacted in such proportions as toobtain the copolymer for the powder coating mixture which has a glasstransition temperature and a molecular weight as set forth above.

A small weight percentage of a catalyst is added to the powder coatingcomposition in order to increase the cross linking rate of the powdercoating composition at the baking temperature thereof. In preference,the catalyst produces a gel time for the powder coating composition ofat least 1 minute but no greater than 40 minutes. The preferred catalystis one which produces a gel time of at least 1 minute but no greaterthan minutes. In general, the catalyst is present in the range of from0.05% by Weight to 1% by weight of the weight of the mixture. The mostdesirable gel time produced by the catalyst is in a time range of fromabout 3 minutes to about 10 minutes. These catalyst gel times are atbaking temperatures for the powder coating compositions in the range of130 C. to 200 C.

The powder coating compositions of this invention may also contain fromabout 6% by weight to about 35% by weight of a pigment. The variouspigments already known in the art may be employed in the powder coatingcompositions. The pigments are generally selected for a color,appearance or corrosion protection properties.

A small weight percent of an antistatic agent may also be employed inthe powder coating composition. For example, 0.05 by weight to 0.5% byweight of the powder coating composition may be an antistatic agent sothat the coating may be applied in an electrostatic spraying operation.

DESCRIPTION OF THE PREFERRED EMBODIMENT A general discussion of thevarious materials which may be employed in the powder coatingcompositions of this invention will be set forth below. Also, aplurality of examples will be employed to show the manner in whichvarious, individual, powder coating compositions, which fall within thescope of this invention, are prepared and utilized.

Th'e principal material in individual powder coating compositions is acopolymer formed from glycidyl methacrylate and an ethylenicallyunsaturated monomer in such proportions as to obtain a copolymer with aglass transition temperature in the range of 40 C. to 90 C. and amolecular weight (M in the range of 2500 to 8500. The ethylenicallyunsaturated monomer employed to form the copolymer is any one, or amixture of, the

many different monomers known to those skilled in the which are employedto form the copolymer with the glycidyl methacrylate are methylmethacrylate, butyl methacrylate, butyl acrylate, ethyl acrylate,2ethylhexyl acrylate. Suitable modifying monomers such as styrene, alphamethyl styrene, acrylonitrile, and methacrylonitrile can be used withthe preferred monomers. When used, a modifying monomer is present in thecopolymer from a weight percent of about 0% by weight to no more thanabout 35% by weight. Thus, when the preferred ethylenically unsaturatedmonomers are used with glycidyl methacrylate to form the copolymer, theglycidyl methacrylate is present in the copolymer from 8% by weight toabout 25% by weight, the modifying monomer is present from about 0% byweight to no more than about 35 by weight, and

the preferred monomer is present from about 92% by weight to about 40%by weight.

In accordance with detailed teachings of this invention, the copolymerfor the powder coating composition. is formed from glycidylmethacrylate, methyl methacrylate,

and butyl methacrylate. In this instance, the glycidyl methacrylate ispresent in the copolymer from about 8% by weight to no more than about25% by weight, the methyl methacrylate is present in the copolymerfromabout 25 by weight to about 60% by weight, and the balance of thecopolymer is butyl methacrylate.

The copolymers of glycidyl methacrylate can be prepared by a variety ofmethods. Generally, a free radical initiator is needed to inducepolymerization reaction. A large number of free radical initiatorsare-known in the art. These include benzoyl peroxide, lauryl peroxide,tbutyl-hydroxyperoxide, acetylcyclohexane sulfonyl peroxide,diisobutyryl peroxide, di(Z-ethylhexyl)peroxydicarbonate, diisopropylperoxydicarbonate, t-butylperoxypivalate,

'decanoyl peroxide, azobis (Z-methylpropionitrile) etc. The

polymerization is preferably carried out in solution using a solvent inwhich the glycidyl methacrylate copolymer is soluble. Toluene, xylene,dioxane, butanone, etc., are suitable solvents-for polymerization. Ifthe glycidyl methacrylate copolymer is prepared in solution, the solidcopolymer can be obtained by evaporating the solvent under vacuum orspray drying techniques. Alternatively, the copolymer can beprecipitated by pouring at a slow rate the solutioninto a non-solventliquid such as hexane, octane or water under a suitable agitationcondition at a slow rate. The copolymer thus obtained should be furtherdried so that it contains less than three percent of the volatileliquids.

Glycidyl methacrylate copolymers can also be prepared by emulsionpolymerization, suspension polymerization, bulk polymerization of theirsuitable combinations. In thesemethods of preparing glycidylmethacrylate copolymers, chain transfer agents may be required tocontrol the molecular weight of the copolymer to a desired range.

For powder coating applications, molecular weight and molecular weightdistribution of the glycidyl methacrylate copolymer is important.Copolymer of average molecular weight (R1,) in the range of 2500 to 8500are suitable. These copolymers, however, must not contam significantamount of higher molecular weight fractions. No more than 2% of thecopolymer can be of molecular weight greater than 20,000. The molecularweight distribution as measured by the ratio of weight average mole ilarweight to number average molecular weight (M /M should be in the rangeof 1.6 to 2.1. The preferred range of molecular weight distribution isin the range of 1.7 to 1.8.

Another one of the materials of individual ones of the'powder coatingcompositions of this invention is a saturated, straight chain,aliphatic, dicarboxylic acid con- -ta1n1ng 4 to 20 carbon atoms permolecule in the amount this invention. The flow control agent forms atleast 0.05 by weight of an individual powder coating. The flow controlagent generally does not exceed about 4% by weight of any individualpowder coating composition.

In general, the flow control agent is a polymer having a molecularweight (lTI of at least 1000. Further, the flow control agent has, atthe baking temperature of the powder coating composition, a lowersurface tension than thesurface tension of the copolymer employed informing the composition.

One" 't ype of material which is used as a flow control agent in thepowder coating compositions is an acrylic polymer having a glasstransition temperature below the glass transition temperature of thecompositions copolymen Some acrylic polymers which are preferred as flowcontrol agents are polylauryl acrylate, polybutyl acrylate andpoly(2-ethylhexyl acrylate). Acrylic polymers to be used as flow controlagents can be prepared by polymerization of the acrylat'or methacrylatemonomers in bulk or insuitable solvent using well known free radicalinitiators.- The amount of the initiator and the polymerizationconditions are chosen so that polymer formed has molecular weight '(ivTabove 1000. The preferred molecular weight range of the acrylate polymeris above 5000. The most preferred range of the acrylate polymer is 6,000to 20,000.

Although polymeric acrylate flow control agents are preferred,fiuorinated' polymers have been found to act as flow control agents forthe powder coating compositions. Such fluorinated polymers are esters ofpolyethyleneglycolor polypropylene glycol and fluorinated fatty acids.Esters'of polyethylene glycol of molecular weight (M y'of'over 2500 andperfluoro octanoic acid are useful as flow control agents forthecompositions of this invention each contain a small, effective,weight percentage of a catalyst. In general, the catalyst is present inan individual composition in a range from 0.05% by weight to 1.0% byweight. The catalyst is selected to produce a gel time for the powdercoating composition greater than at least 1 minute at the bakingtemperature of the composition. A suitable catalyst is also one whichwill produce a gel time that does not exceed 40 minutes. As used herein,the gel time of a coating composition is that time in which the coatingcomposition develops elasticity and resistance to flow at the bakingtemperature.

Some catalysts which are suitable for use in the powder coatingcomposition include tetralkylammonium salts, imidazole type catalysts,tertiary. amines, triaryl phos phates and metal salts of organiccarboxylic acids. The tetralkyl-ammonium salts catalysts include thefollowing: tetrabutyl ammonium bromide, tetrabutyl ammonium chloride,tetrabutyl ammonium iodide, tetraethyl ammonium chloride (bromide oriodide), tetramethyl ammonium chloride, dodecyl dimethyl(2-phenoxyethyl) ammonium bromide and diethyl(2-hydroxy ethyl) methylammonium bromide. Suitable catalysts of the imidazole type include:2-methyl-4-ethyl imidazole, 2-methyl imidazole,imidazole,2-[(N-benzylanilino) methyl]-2- imidazoline' phosphate, and2-benzyl-2-imidazoline hydrochloride. Suitable tertiary amine catalystfor the powder coating compositions of this invention include:triethylenediamine, N,N-diethylcyclohexylamine, and N-methyl morpholine.The metal'salts of organic carboxylic acid which are catalystfor thepowder coatings of this invention include, but are not limited to:stannous octoate, zinc naphthenate, cobalt naphthenate, zinc octoate,stannous 2-ethylhexoate, phenylmercuric propionate, lead neodecanoate,dibutyl tin dilaurate and lithium benzoate. An example oftriarylphosphate type catalyst is triphenylphosphate.

' a The catalyst used in an individual powder coating composition ispreferably solid at room temperature and has a melting point of from 50C. to 200 C. As previously specified, the catalyst is present in apowder coating composition from 0.05 by weight to 1.0% by weight of thetotal weight of the powder composition. Further, the catalyst produces agel time of at least 1 minute and no greater than 40 minutes. Generally,the preferred gel time of the composition is in the range 'of from 1minute to approximately 10 minutes at the baking temperature of thecomposition.

::- :Since individual powder coating compositions of this invention canbe applied to an article to be painted by electrostatic methods, it ispreferred to include a small weight percentage of an antistatic agent insuch compositions so that the deposition thereof is accomplished in aproper manner. In particular, the antistatic agent is included in arange from 0.05% to 1.0% by weight of the total powder composition.Suitable antistatic agents include, but are not limited to,tetralkylammonium salts as discussed previously and which also serve ascatalysts. Other suitable antistatic agents include: alkyl-poly(ethyleneoxy) phosphates as, for example, dibutyl-poly (ethyleneoxy)phosphate or alkylaryl poly (ethyleneoxy) phosphates, as, for example,ethyl benzyl poly(ethyleneoxy) phosphate.

In order to give individual powder coating compositions of thisinvention a suitable color, a pigment is included in the coatingcomposition. In general, the pigment forms from about 6% by weight toabout 35% by weight of the total powder coating composition. Pigmentswhich are suitable for powder coating compositions include, but are notlimited to, the following: basic lead silico chromate 30% by weight(orange); titanium dioxide 30% by weight (white); titanium dioxide 15%by weight plus ultra marine blue 10% by weight (blue); phthalocyanineblue 7% by weight plus titanium dioxide 10% by weight (blue);phthalocyanine green 7% by weight plus titanium dioxide 10% by weight(green); ferrite yellow 7% by weight plus titanium dioxide 10% by weight(yellow); carbon black pigment 6% by weight (black); black iron oxide10% by weight (black); chrominum green oxide 8% by weight plus titaniumudioxide 10% by weight (green); quindo red 5% by weight plus titaniumdioxide 16% by weight (red); and iron oxide transparent orange pigment10 by Weight (orange).

Having generally described the various materials which are employed informulating the powder coating compositions of this invention, aplurality of examples will be set forth to illustrate various individualpowder coating compositions.

EXAMPLE 1 The monomers, glycidyl methacrylate 15 by weight, methylmethacrylate 45% by weight and butyl methacrylate 40% by weight aremixed together. Three weight percent of a catalyst2,2'-azobis-(Z-methylpropionitrile) (AIBN) is dissolved in the monomermixture. The mixture is slowly added to refluxing toluene parts) whichis stirred vigorously under a nitrogen atmosphere. A condenser isprovided at the top of the toluene container to condense the toluenevapors and return them to the container. The monomer mixture is addedthrough a regulating valve and the rate of addition is controlled tomaintain a reflux temperature (109 C.112 C.) with only a small fractionof heat supplied from an external heater. After the addition of themonomer mixture is complete, the refluxing is maintained by externalheat source for 3 additional hours.

The solution is poured into shallow stainless steel trays. These traysare placed in a vacuum oven and the solvent evaporated therefrom. As thesolvent is removed, the copolymer solution becomes more concentrated.The temperature of the vacuum oven is raised to about 110 C. Drying iscontinued until the solvent content of the copolymer is below 3 percent.The trays are cooled and the copolymer collected and ground to passthrough 20 mesh screen. The copolymer has a glass transitiontemfiggzature of 53 C. and a molecular weight (11,) of

One hundred parts by weight of the ground copolymer are mixed with thefollowing materials:

Parts Azelaic acid 10.0- Tetrabutyl ammonium bromide 0.2 Polyaurylacrylate (M =10,000) 0.5 Titanium dioxide 30 The materials are mixedtogether in a ball mill for 2 hours. The mixture is milled rolled at 85C. to 90 C. for 5 minutes. The solid obtained is ground in a ball millto pass through a 140 mesh screen.

The resulting powder thus obtained is a powder coating composition ofthe invention. The powder is sprayed on an electrically grounded, steelpanel by using electrostatic powder spray gun operating at 50 kv.charging voltage. After spraying, the panel is heated at 175 C. forminutes.

The coating obtained on the panel has good adhesion to the steel paneland good impact strength. The coating also is applied to and has goodadhesion on panels of glass, brass, zinc, aluminum, copper and bronze.The coating obtained is not soluble in toluene, gasoline, butanone ormethanol.

EXAMPLE 2 The procedure of Example 1 is repeated. The formation of thecopolymer, however, begins with a monomer mixture having glycidylmethacrylate 8% by weight, methyl methacrylate 52% by weight and butylmethacrylate 40% by weight. Three weight percent of the catalyst AIBN isemployed. When the procedure of Example 1 is followed, the resultingcopolymer has a glass transition temperature of 58 C. and a molecularweight of 4000.

One hundred parts of the copolymer produced is mixed with the sameadditional ingredients set forth in Example 1, except using 5.3 parts ofazelaic acid. The quality of the painted panels obtained afterapplication of the pow der coating to various materials is about thesame as achieved in Example 1.

EXAMPLE 3 A monomer mixture having the following composition isprepared: glycidyl methacrylate 12% by weight, methyl methacrylate 48%by weight, and butyl methacrylate 40% by weight. The monomer mixture isprocessed in the same manner as described in Example 1 with 3% by weightof the catalyst AIBN employed. The resulting copolymer has a glasstransition temperature of 56 C. and a molecular weight of 4000. Onehundred parts of the copolymer produced is mixed with the same additioningredients described in Example 1, except 8.0 parts azelaic acid areused.

The powder coating composition obtained by following the process stepsset forth in Example 1 is applied to test panels in the same manner asdescribed in Example 1. The coating is baked at a temperature of 170 C.for minutes. The coating obtained has good adhesion to steel, glass,brass, zinc, aluminum, copper and bronze.

EXAMPLE 4- A monomer mixture having the following composition isprepared: glycidyl methacrylate 20% by weight, methyl methacrylate byweight and butyl methacrylate 40% by weight. A copolymer is formed fromthis monomer mixture in accordance with the same procedure as isoutlined in Example 1 In this case, 1% by weight of the catalyst AIBN isadded. The copolymer produced has a glass transition temperature of 51C. and a molecular weight of 8500.

The ground copolymer (100 parts by weight) is added to the followingmaterials:

Parts Adipic acid 10.3 Tetrabutylammom'um chloride 0.1 Polybutylacrylate(1%:9000) 4 Titanium dioxide 15 Ultramarine blue 10 The aboveingredients are mixed together and processed in accordance with theprocedure of Example 1 to obtain a powder coating composition. Thepowder coating composition is sprayed on various test panels of steel,glass, brass, zinc, aluminum, copper and bronze. The coating obtained oneach test panel after curing of the powder coating composition at atemperature of 200 C. for 10 minutes is of good quality, and is solventand scratch resistant.

EXAMPLE 5 A monomer mixture having the following composition isprepared: glycidyl methacrylate 25% by Weight, methyl methacrylate 40%by weight and butyl methacrylate 35% by weight. The monomers are reactedas described in Example 1 to produce a copolymer. In this case, 6% byweight of the catalyst AIBN is employed. The resulting copolymer has aglass transition temperature of 5 3 C. and a molecular weight of 2000.

One hundred parts by weight of the copolymer obtained is mixed with thefollowing materials:

Parts Pimelic acid 14.2 2-methyl-4-ethylimidazole 0.05 Dibutylpoly(ethyleneoxy) phosphate 0.05 Polyisododecylmethacrylate 4 Titaniumdioxide l0 Phthalocyanine blue 7 A powder coating composition isobtained by following the process steps set forth in Example 1. Thecoating composition is applied to a series of test panels and baked atthe temperature of and for the same time as Example 4. The coatingobtained on the various test panels is of poor quality with respect toits adhesion appearance and impact characteristics.

EXAMPLE 6 'Parts Suberic acid 9.3 Triethylene diamine 0.1Tetraethylammonium chloride .05 Polylaurylmethacrylate (M =6000) 2Phthalocyanine green 7 Titanium dioxide 10 The above described materialsare processed as described in Example 1 in order to produce a powdercoating composition. The powder coating composition is applied to testpanels as described in Example 1 and baked on the panels at atemperature of 150 C. for 15 minutes.

The coating obtained has good adhesion to steel, glass, brass, zinc,aluminum, copper and bronze and is insoluble in toluene, gasoline,methanol and butanone.

EXAMPLE 7 A monomer mixture having the following composition isprepared: glycidyl methacrylate 15% by weight, methyl methacrylate 50%by weight and styrene 35% by weight. The monomers are reacted inaccordance with the procedure set forth in Example 1 with 3% by weightof the catalyst AIBN being utilized. The resulting ground copolymer hasa molecular weight of 4500 and a glass transition temperature of C.

9 One hundred part by Weight of the copolymer obtained is added to thefollowing materials:'

. Parts Sebacic acid 10.8 Tetramethylammonium chloride 1Poly(2-ethylhexy1 acrylate) 2 Ferrite yellow 7 Titanium dioxide 10 Thismixture is processed as described in Example 1 in order to form a powdercoating composition. The powder coating composition is applied to testpanels as described in. Example 1. The panels are baked at a temperatureof. 180 C. for minutes. The adhesion quality of the powder coating afterbaking on the various test panels is gOOd. The coating on each panelpossesses good solvent and scratch resistance.

EXAMPLE 8 .-A monomer mixture having the following compositions isformed: glycidyl methacrylate 18% by weight, ethyl acrylate 20% byWeight, methyl methacrylate 40% by weight, vinyl chloride22% by weight.The monomer mixture is polymerized by using 2 weight percent of thecatalyst AIBN as the initiator.

One hundred parts of the ground copolymer obtained is added to thefollowing materials:

Parts Tetradecandioc acid 16.4 Trimethyl benzyl ammonium chloride 0.1Poly(2-ethylhexyl acrylate) (M =11,000) 2 Carbon black 6 The abovematerials are mixed and processed as set forth in Example 1. Theresulting powder coating composition is applied to test panels asspecified in Example 1. The coating composition is baked at 170 C. for15 minutes. All the painted panels exhibit good adhesion and solventresistance properties.

EXAMPLE 9 'Parts Brassylic acid 13 Dodecyldimethyl (2-phenoxy-ethyl)ammonium bromide (M =3400) 0.5 Polyethylene glycol perfluoro octanoate 2Black iron oxide The mixture so formed is processed as described inExample 1 to produce a powder coating composition. This powder coatingcomposition is applied to test panels as it .is described in Example 1.The coated panels are baked .at 165 C. for minutes. The coating on eachpanel has good adhesion and solvent resistance.

"EXAMPLE 10 .A monomer mixture having the following composition isprepared: glycidyl methacrylate 5% by weight, methyl methacrylate 55% byweight, and butyl methacrylate 40% by weight.. The monomer mixture isreacted as described in Example 1 with 6% by weight of the catalystAIBN. The resulting copolymer has a glass transition temperature'of 55C. and a molecular weight of 3000.

I 'Oneihundred parts by Weight of the ground copolymer is mixed withthefollowing materials:

Parts Azelaic acid 3.34 Tetraethylammonium bromide 1 Ethyl benzyl(ethyleneoxy) phosphate .5 Poly(2-ethyll1exyl acrylate) 04 Chromiumgreen oxide 8 Titanium dioxide 10 The above mixture is processed asdescribed in Example 1 to produce a powder coating composition.

The powder coating composition is applied to a plurality of test panels.The panels are baked at a temperature of 170 C. for 20 minutes. Theadhesion to the test panels of the powder coating material is poor andcoating has a tendency to chip and crack.

EXAMPLE 11 A monomer mixture is formed having the following composition:glycidyl methacrylate 12% by weight, methyl methacrylate 50% by weight,Z-ethylhexyl acrylate 10% by weight and acrylonitrile 28% by weight. Themonomer mixture is processed as set forth in Example 1 in order to forma copolymer. Four percent by weight of the catalyst AIBN is added. Thecopolymer formed has a glass transition temperature of 60 C. and amolecular weight of 4000.

One hundred parts by weight of the ground copolymer is mixed with thefollowing materials:

Parts Nonadecandioic acid 27.8

'Stannous octoate 0.5 Tetraethylammonium bromide .05 Polyethylene glycolperfiuoro octanoate 2 Quindo red 5 Titanium dioxide 15 The mixture abovedescribed is processed as set forth in Example 1 to produce a powdercoating composition. The powder coating composition is applied to testpanels as described in Example 1. The panels are baked at 150 C. for 20minutes. The adhesion to the panels of the powder coating is good andthe coating possesses good solvent resistance.

EXAMPLE 12 A monomer mixture having the following composition isprepared: glycidyl methacrylate 22% by weight, nhexyl methacrylate 20%by weight, butyl methacrylate 25% by weight and acrylonitrile 33% byweight. A copolymer is formed from this monomer mixture in accordancewith the same procedure as is outlined in Example 1. In this case, 1.5%by weight of the catalyst AIBN is added. The copolymer produced has aglass transition temperature of 40 C. and a molecular Weight of 7500.

The ground copolymer parts by weight) is added to the followingmaterials:

Parts Docosandioic acid 27.2

Zinc octoate 0.8 Tetrabutylammonium iodide 1.0 Polybutyl acrylate 2.0Iron oxide transparent orange 10 The above ingredients are mixedtogether and processed in accordance with the procedure of Example 1 toobtain a powder coating composition. The powder coating composition issprayed on various test panels of steel, glass, brass, zinc, aluminum,copper and bronze. The coating obtained on each test panel after curingof the powder coating composition at a temperature of C. for 20 minutesis of good quality, and is solvent and scratch resistant.

EXAMPLE 13 A monomer mixture having the following composition isprepared: glycidyl methacrylate 10% by weight, methyl methacrylate 45%by Weight, butyl methacrylate 35% by 1 1 weight and vinyl acetate 10% byweight. A copolymer is formed from this monomer mixture in accordancewith the same procedure as is outlined in Example 1. In this case, 3% byweight of the catalyst AIBN is added.

The ground copolymer (100 parts by weight) is added to the followingmaterials:

Parts Adipic acid 5.0 Tetrabutylammonium bromide 2 Poly(2-ethylhexylacrylate) 3.5 Carbon black 6 The above ingredients are mixed togetherand processed in accordance with the procedure of Example 1 to obtain apowder coating composition. The powder coating composition is sprayed onvarious test panels. The coating obtained on each test panel aftercuring of the powder coating composition at a temperature of 160 C. for10 minutes is of good quality. Also, the coating obtained on each testpanel is insoluble in toluene, gasoline, methanol and butanone.

EXAMPLE 14 A monomer mixture having the following composition isprepared: glycidyl methacrylate 8% by weight, methyl methacrylate 52% byWeight and isobutyl methacrylate 40% by weight. A copolymer is formedfrom this monomer mixture in accordance with the same procedure as isoutlined in Example 1. In this case, by weight of the catalyst AIBN isadded. The copolymer produced has a glass transition temperature of 75C. and a molecular weight of 3200.

The ground copolymer (100 parts by weight) is added to the followingmaterials:

Parts Succinic acid 3.7 Tetrabutylammonium bromide 2 Polylauryl acrylate4 Titanium dioxide 30 The above ingredients are mixed together andprocessed in accordance with the procedure of Example 1 to obtain apowder coating composition. The powder coating composition is sprayed onvarious test panels of steel, brass, glass, zinc, aluminum, copper andbronze. The coating obtained on each test panel after curing of thepowder coat ing composition at a temperature of 130 C. for minutes is ofgood quality and is solvent and scratch resistant.

EXAMPLE 15 A monomer mixture having the following composition isprepared: glycidyl methacrylate 10% by weight, methyl methacrylate 67%by weight, and n-butyl methacrylate 23% by weight. A copolymer is formedfrom this monomer mixture in accordance with the procedure as isoutlined in Example 1. In this case, 4% by weight of the catalyst AIBNis added. The copolymer produced has a glass transition temperature of73 C. and a molecular weight of 3000.

The ground copolymer (100 parts by weight) is added to the followingmaterials:

Parts Undecandioic acid 8.6 Tetrabutylammonium chloride 0.7 Polybutylacrylate 2 Titanium dioxide The above ingredients are mixed together andprocessed in accordance with the procedure of Example 1 to obtain a.powder coating composition. The powder coating composition is sprayed onvarious test panels. The coating obtained on each test panel aftercuring of the powder coat ing composition at a temperature of 180 C. for15 minutes is of good quality. Also, each of the test panel coatings isresistant to and insoluble in toluene, gasoline, methanol and butanone.

12 EXAMPLE 16 A monomer mixture having the following composition isprepared: glycidyl methacrylate 15% by weight, methyl methacrylate 32%by weight, ethyl acrylate 15% by weight, isobutyl acrylate 8% by weightand styrene 30% by weight. A copolymer is formed from this monomermixture in accordance with the same procedure as is outlined inExample 1. In this case, 3% by weight of the catalyst AIBN is added.

The ground copolymer parts by weight) is added to the followingmaterials:

Parts Glutaric acid 6.6 Tetraethylammonium bromide 1 Polyisodecylmethacrylate (M =5000) 1.5 Titanium dioxide 30 The above ingredients aremixed together and processed in accordance with the procedure of Example1 to obtain a powder coating composition. The powder coating compositionis sprayed on various test panels of steel, glass, brass, zinc,aluminum, copper and bronze. The coatings obtained on each test panelafter curing of the powder coating composition at a temperature of C.for 15 minutes is of good quality and has good adhesion characteristics.The powder coating composition on each panel is resistant to thesolvents previously mentioned.

EXAMPLE 17 A monomer mixture having the following composition isprepared: glycidyl methacrylate 15% by weight, methyl methacrylate 40%by weight, 2-ethylhexyl acrylate 15% by weight, alpha methyl styrene 20%by weight and acrylonitrile 10% by weight. A copolymer is formed fromthis monomer mixture using 4% by weight of the catalyst AIBN.

The ground copolymer (100 parts by weight) is added to the followingmaterials:

Parts Adipic acid 7.7 Tetraethylammonium bromide 0.4 Poly(2-ethylhexylacrylate) 2 Titanium dioxide 30 The above ingredients are mixed togetherand processed in accordance with the procedure of Example 1 to obtain apowder coating composition. The powder coating composition is sprayed onvarious test panels of steel, glass, brass, zinc, aluminum, copper andbronze. The coating obtained on each test panel after curing of thepowder coating composition at a temperature of C. for 20 minutes is ofgood quality and resistant to the aforementioned solvents.

EXAMPLE 18 Parts Azelaic acid 13.4 Tetraethylammonium bromide 0.5Polylauryl acrylate 1.0 Titanium dioxide a... 30

The above ingredients are mixed together and processed in accordancewith the procedure of Example 1 to obtain a powder coating composition.The powder coating composition is sprayed on various test panels ofsteel, glass,

brass, zinc, aluminum, copper and bronze. The coating obtained on eachtest panel after curing of the powder coating composition at atemperature of 180 C. for 10 minutes is of good quality and is resistantto the aforementioned solvents.

EXAMPLE 19 Parts Azelaic acid 8.0 Tetraethylammonium bromide 1.0Polylauryl acrylate 0.5 Titanium dioxide 30 The above ingredients aremixed together and processed in accordance with the procedure of Example1 to obtain a powder coating composition. The powder coating compositionis sprayed on various test panels of steel, glass, brass, zinc,aluminum, copper and bronze. The coating obtained on each test panelafter curing of the powder coating composition at a temperature of 130C. for 30 minutes is of good quality and resistant to the aforementionedsolvents.

EXAMPLE 20 A monomer mixture having the following composition isprepared: glycidyl methacrylate 15 by weight, Z-ethylhexyl acrylate 10%by weight, methyl methacrylate 50% by weight, methacrylonitrile 15% bywegiht and alpha methyl styrene 10% by weight. A copolymer is formedfrom this monomer mixture in accordance with the same procedure as isoutlined in Example 1. In this case, 4% by weight of the catalyst AIBNis added.

The ground copolymer (100 parts by weight) is added to the followingmaterials:

Parts Azelaic acid 11.1 Tetraethylammonium bromide 0.5 Polylaurylacrylate 2.5 Titanium dioxide 30 The above ingredients are mixedtogether and processed in accordance with the procedure of Example 1 toobtain a powder coating composition. The powder coating composition issprayed on various test panels of steel, glass, brass, zinc, aluminum,copper and bronze. The coating obtained on each test panel after curingof the powder coating composition at a temperature of 135 C. for 30minutes is of good quality. Also the coatings are resistant to andinsoluble in toluene, gasoline, methanol. and butanone.

The use of glycidyl methacrylate copolymers and dicarboxylic acid crosslinking agents in a liquid paint system is described in US. Patent2,857,354. However, the powder coating compositions of this inventionare substantially different than the liquid paint compositions describedin the examples of that patent. This difference can be best illustratedby attempting to prepare powder coating compositions by evaporating thesolvents from the liquid paint systems described in the examples of thepatent. Dry powders cannot be prepared from the compositions of Examples4 and 5 of the patent. Powders prepared from the compositions ofExamples 1, 2, 3, and 6, when deposited on a metal panel, do not fusetogether to form a film when the panels are baked at 150 to 200 C. for20 minutes. The baked coatings on test panels are not smooth, butrather, are rough. Also the baked coatings possess very low gloss, andhave a lack of flexibility and adhesion. It, therefore, can be concludedthat compositions which are generally suitable for liquid paint systemsare not necessarily suitable for powder paints by simply evaporating thesolvents therefrom.

The use of a dicarboxylic acid as a cross linking agent for glycidylmethacrylate terpolymers is mentioned in US. Patent 3,058,947. In orderto test these materials, compositions of Example VII of this patent aredried by evaporating solvents under vacuum. The materials are ground topass through a 200 mesh screen.: Samples of the ground powder aredeposited on metal panels and baked at 160 C. for 45 minutes. Thecoatings obtained show an abundance of craters, are inferior in glossand smoothness, and lack the impact properties described in the ExampleVII. It is, therefore, concluded that there is a substantial differencein paint films produced on a panel when the coating is produced on onehand by a liquid system, and, on the other hand, by a powder system.Other improvements specific to the powders are needed in order to obtainpaints of acceptable quality. The reason for the difference between theproperties and apperance of powder coatings derived by solventevaporation from a liquid coating and the liquid coatings itself are notclear. It is, however, certain that the powders obtained by dryingliquid paint compositions are not useful for powder coatingcompositions.

There has been disclosed herein powder coating compositions which may beemployed in the painting of articles. Many modifications of thisinvention will be apparent to those skilled in the art in view of thisspecification. It is intended that all such modifications which fallwithin the scope of this invention be included within the appendedclaims.

What I claim is:

1. A powder coating composition comprising a mixture of:

(A) a copolymer of a glycidyl ester of a monoethylenically unsaturatedacid and an ethylenically unsaturated compound in such proportions as toobtain a copolymer with a glass transition temperature in the range of40 C. to C. and a molecular weight (M in the range of 2500 to 8500, saidglycidyl ester being present in the copolymer from at least about 8% byweight to no more than about 25 by weight;

(B) a saturated, straight chain, aliphatic, dicarboxylic acid containing4-20 carbon atoms per molecule in the amount of 0.8 to 1.1 carboxylicgroups for each epoxy group in the copolymer; and

(C) a flow control agent forming from at least 0.05 to 4.0% by weight ofthe mixture, said flow control agent being a polymer having a molecularweight (M of at least 1000, said flow control agent further being apolymer or copolymer selected from the group consisting of acrylateeters, methacrylate esters and polyethylene or polypropylene glycolesters of fluorinated fatty acids.

2. The powder coating composition of claim 1 further comprising: (D) asmall weight percent of a catalyst which produces a gel time for thepowder coating composition greater than 1 minute at the bakingtemperature of the composition.

3. The powder coating composition of claim 2 further comprising: apigment forming from about 6% by weight to about 35% by weight of thetotal mixture.

4. The powder coating composition of claim 3 further comprising: a smallweight percentage of an antistatic agent.

5. The powder coating composition of claim 1 wherein: said straightchain, aliphatic, dicarboxylic acid is selected from the groupconsisting of adipic acid, pimelic acid, suberic acid, azelaic acid,sebacic acid, undecandioic acid and brassylic acid.

6. A powder coating composition comprising a mixture of:

(A) a copolymer of a glycidyl ester of a mono-ethylenically unsaturatedacid and an ethylenically unsaturated compound in such proportions as toobtain a copolymer with a glass transition temperature in the range of50 C. to 80 C. and a molecular weight (fi in the range of 3000 to 6500,said glycidyl ester being present in the copolymer from at least about10% by weight to no more than about 20% by weight;

(B) a saturated, straight chain, aliphatic, dicarboxylic acid containingto 13 carbon atoms per molecule in the amount of 0.8 to 1.1 carboxylicgroups for each epoxy group in the copolymer;

(C) a flow control agent forming from at least about 0.05% to about 4.0%by weight of the mixture, said flow control agent being a polymer havinga molecular weight (M of at least 1000, said flow control agent furtherbeing a polymer or copolymer selected from the group consisting ofacrylate esters, methacrylate esters and polyethylene or polypropyleneglycol esters of fluorinated fatty acids; and

(D) a small weight percentage of a catalyst which produces a gel timefor the powder coating composition at the compositions bakingtemperature of at least 1 minute and no greater than 40 minutes.

7. The powder coating composition of claim 6 further including: apigment forming from about 6% by weight to about 35% by weight of thetotal mixture.

8. The powder coating composition of claim 6 further including: a smallweight percentage of an antistatic agent.

9. The powder coating composition of claim 6 wherein: said dicarboxylicacid is selected from the group consisting of adipic acid and azelaicacid.

10. A powder coating composition comprising a mixture of:

(A) a copolymer of a glycidyl ester of a mono-ethylenically unsaturatedacid and an ethylenically unsaturated compound in such proportions as toobtain a copolymer with a glass transition temperature in the range of60 C. to 70 C. and with a molecular weight (M,,) in the range of 3000 to4000, said glycidyl ester being present in the copolymer from at leastabout 12% by weight to no more than about 18% by weight;

(B) a saturated, straight chain, aliphatic, dicarboxylic acid containing5 to 13 carbon atoms per molecule in the amount of 0.8 to 1.1 carboxylicgroups for each epoxy group in the copolymer;

(C) a flow control agent forming from at least 0.05% to about 4.0% byweight of the mixture, said flow control agent being a polymer having amolecular weight (FL) of at least 1000, said flow control agent furtherbeing a polymer or copolymer selected from the group consisting ofacrylate esters, methacrylate esters and polyethylene, or polypropylvene glycol esters of fiuorinated fatty acids; and

(D) a small weight percentage of a catalyst which produces a gel timefor the coating composition at its baking temperature of at least 1minute and no greater than minutes.

11. The powder coating composition of claim 10 further including: apigment forming from about 6% by weight to about 35% byv weight of thetotal mixture.

12. The powder coating composition of claim 10 further including: asmall weight percentage of an antistatic agent.

13. The powder coating composition of claim 10 where in: saiddicarboxylic acid is selected from the group consisting of adipic acidand azelaic acid.

14. A powder coating composition comprising a mixture of:

(A) a copolymer of a glycidyl ester of a mono ethylenically unsaturatedacid and an ethylenically unsaturated compound in such proportions as toobtain a copolymer with a glass transition temperature in the range of60 C. to -70 C. and a molecular weight (fi in the range of 3000 to 4000,said glycidyl ester being present in the copolymer at about 15% byweight;

(B) a dicarboxylic acid selected from the group consisting of adipicacid and azelaic acid, said acid being present in the amount of 0.8 to1.1 carboxylic group for each epoxy group in the copolymer;

(C) a flow control agent forming from at least 0.05 to about 4.0% byweight of the mixture, said flow control agent being a polymer having amolecular weight (11,) of at least 1000, said flow control agent furtherbeing a polymer or copolymerselected from the group consisting ofacrylate esters, methacrylate esters 'and' polyethylene or polypropyleneglycol esters of fluorinated fatty acids; and

(D) a small weight percentage of a catalyst sufiicient to give thepowder coating composition at its baking temperature a gel time from atleast 3 minutes to no more than 10 minutes.

15. The powdery coating composition comprising a mixture of:

(A) a copolymer of a glycidyl ester of a monoethylenically unsaturatedacid and (1) an ethylenically unsaturated monomer selected from thegroup consisting of methyl methacrylate, butyl methacrylate, butylacrylate, ethyl acrylate, and Z-ethylhexyl acrylate; and (2) a modifyingmonomer selected from the group consisting of styrene, alpha methylstyrene, acrylonitrile and methacrylonitrile, in such proportions as toobtain a copolymer having a glass transition temperature in the range of40 C. to C. and a molecular weight (M,,) in the range of 2500 to 8500,said glycidyl ester being present in the copolymer from at least about8% by weight to no more than 25% by weight, said modifying monomer beingpresent in the copolymer from 0% by weight to no more than about 35 byweight;

(B) a saturated, straight chain, aliphatic, dicarboxylic acid containing420 carbon atoms per molecule in the amount of 0.8 to 1.1 carboxylicgroups for each epoxy group in the copolymer;

(C) a flow control agent forming from at least 0.05

- to about 4.0% by Weight of the mixture, said flow control agent beinga polymer having a molecular weight (M1,) of at least 1000, said flowcontrol agent further being a polymer or copolymer selected from thegroup consisting of arcylate esters, methacrylate esters andpolyethylene or polypropylene glycol esters of fluorinated fatty acids;and

(D) a small weight percentage of a catalyst which results in a gel timefor the powder coating composition at its baking temperature of at least1 minute but no greater than 40 minutes.

16. The powder coating composition of claim 15 wherein: a pigment isincluded which forms from about 6% by weight to about 35 by weight ofthe total mixture of the powder coating composition.

17. The powder coating composition of claim 15 where in: a small weightpercentage of an antistatic agentis added.

18. The powder coating composition of claim 15 wherein: saiddicarboxylic acid is selected from the group consisting of adipic acid,pimelic acid, suberic acid, azelaic acid, sebacic acid, undecandoic acidand brassylic acid.

19. A powder coating composition comprising a mixture of:

(A) a copolymer of a glycidyl ester of a mono-ethylenically unsaturatedacid and (1) an ethylenically unsaturated monomer selected from thegroup consisting of methyl methacrylate, butyl methacrylate, butylacrylate, ethyl acrylate, and Z-ethylhexyl acrylate, and (2) a modifyingmonomer selected from the group consisting of styrene, alpha methylstyrene, acrylonitrile and methacrylonitrile in such proportions as toobtain a copolymer having a glass transition temperature in the range of50 C. to 80 C. and a molecular weight (M in the range of 3000 to 6500,said glycidyl ester being present in the copolymer from at least 10% byweight to no more than 20% by weight, said modifying monomer beingpresent in said copolymer from by weight to no more than about 35% byweight;

(B) a saturated, straight chain, aliphatic, dicarboxylic acid containing5 to 13 carbon atoms per molecule in the amount of 0.8 to 1.1 carboxylicgroup for each epoxy group in the copolymer;

(C) a flow control agent forming from at least about 0.5% to about 4.0%by weight of the mixture, said flow control agent being a polymer havinga molecular Weight (M of at least 1000, said flow control agent furtherbeing a polymer or copolymer selected from the group consisting ofacrylate esters, methacrylate esters and polyethylene or polypropyleneglycol esters of fiuorinated fatty acids; and

(D) a small weight percentage of a actalyst sufiicient to produce a geltime for the powder coating composition at its baking temperature of atleast 1 minute but no greater than 40 minutes.

20. The powder coating composition of claim 19 further including: apigment which forms from about 6% by weight to about 35% by weight ofthe total mixture of the powder coating composition.

21. The powder coating composition of claim 19 further including: asmall weight percentage of an antistatic a ent.

22. The powder coating composition of claim 19 wherein: saiddicarboxylic acid is selected from the group consisting of adipic acidand azelaic acid.

23. A powder coating composition comprising a mixture of:

(A) a copolymer of a glycidyl ester of a mono-ethylencially unsaturatedacid, and (1) an ethylenically unsaturated monomer selected from thegroup consisting of methyl methacrylate, butyl methacrylate, butylacrylate, ethyl acrylate, and 2-ethylhexyl acrylate, and (2) a modifyingmonomer selected from the group consisting of styrene, alpha methylstyrene, acrylonitrile and methacrylonitrile in such proportions as toobtain a copolymer having a glass transition temperature in the range of60 C. to 70 C. and a molecular weight (M,,) in the range of 3000 to4000', said glycidyl ester being present in the copolymer from at leastabout 12% by weight to no more than 18% by weight, said modifyingmonomer being present in said copolymer from 0%} by weight to no morethan about 35% by weight;

(B) a saturated, straight chain, aliphatic, dicarboxylic acid containing5 to 13 carbon atoms per molecule in the amount of 0.8 to 1.1 carboxylicgroups for each epoxy group in the copolymer;

(C) a flow control agent forming from at least about 0.5% to about 4.0%by weight of the mixture, said flow control agent being a polymer havinga molecular weight (M of at least 1000, said flow control agent furtherbeing a polymer or copolymer selected from the group consisting ofacrylate esters, methacrylate esters and polyethylene or polypropyleneglycol esters of fiuorinated fatty acids; and

(D) a small weight percentage of a catalyst sufiicient to produce a geltime for the powder coating composition at its baking temperature of atleast 1 minute but no greater than minutes.

24. The powder coating composition of claim 23 further including: apigment which forms from about 6% by weight to about 35% by weight ofthe total mixture.

25. The powder coating composition of claim 23 further including: asmall weight percentage of an antistatic agent.

26. The powder coating composition of claim 23 wherein: dicarboxylicacids are selected from the group consisting of adipic acid and azelaicacid.

27. The powder coating composition of claim 24 wherein: said mixtureforming said powder coating composition has a particle size in the rangefrom 10 microns to 100 microns.

28. The powder coating composition of claim 24 wherein: the size rangeof the particles forming the powder coating composition is in the rangeof 40 to 75 microns.

29. A powder coating composition comprising a mixture of:

(A) a copolymer of a glycidyl ester of a mono-ethylenically unsaturatedacid and (1) an ethylenically unsaturated monomer selected from thegroup consisting of methyl methacrylate, butyl methacrylate, butylacrylate, ethyl acrylate, and 2-ethylhexyl acrylate, and (2) a modifyingmonomer selected from the group consisting of styrene, alpha methylstyrene, a-crylonitrile and methacrylonitrile in such proportions as toobtain a copolymer having a glass transition temperature in the range of60 C. to 70 C. and a molecular weight (fi in the range of 3000 to 4000,said glycidyl ester being present in the copolymer in the range of about15% by weight, said modifying monomer being present in said copolymerfrom 0% by weight to no more than 35% by weight;

(B) a dicarboxylic acid selected from the group consisting of adipicacid and azelaic acid in the amount of 0.8 to 1.1 carboxylic group foreach epoxy group in the copolymer;

(C) a flow control agent forming from at least about 0.05% to about 4.0%by weight of the mixture, said flow control agent being a polymer havinga molecular weight (M of at least 1000, said flow control agent furtherbeing a polymer or copolymer selected from the group consisting ofacrylate esters, methaciylate esters and polyethylene or polypropyleneglycol esters of fiuorinated fatty acids; and

(D) a small weight percentage of a catalyst which gives to the mixture agel time at its baking temperature of at least 3 minutes but not inexcess of 10 minutes.

30. The powder coating composition as defined in claim 29 furtherincluding from 6% to about 35% by weight of a pigment.

31. A powder coating composition comprising a mixture of:

(A) a copolymer of glycidyl methacrylate, ethyl methacrylate and butylmethacrylate, said glycidyl methacrylate being present in the copolymerfrom about 8% by weight to no more than about 25% by weight, said methylmethacrylate being present in the copolymer from about 15 by weight toabout 52% by weight with the balance of the copolymer being said butylmethacrylate, the copolymer having a glass transition temperature in therange of 40 C. to C. and a molecular weight (M in the range of 2500 to8500;

(B) a saturated, straight chain, aliphatic, dicarboxylic acid containing4 to 20 carbon atoms in the amount of 0.8 to 1.1 carboxylic groups foreach epoxy group in the copolymer;

(C) a flow control agent forming from at least 0.05

to about 4.0% by weight of the mixture, said flow control agent being apolymer having a molecular weight (R1,) of at least 1000, said flowcontrol agent further being a polymer or copolymer selected from thegroup consisting of acrylate esters, methacrylate 1 9 20 esters andpolyethylene or polypropylene glycol esters References Cited Offluorinated fatty acids; and (D) a small weight percentage of a catalystsufiicient to cause the coating composition mixture to have a gel3,322,419 12/1965 Jubilee 260-456 time of at least 1 minute but nogreater than 40 5 70,564 12/1962 Rqeser 260-836 minutes 3,423,481 1/1969 Mlzutanr 260 836 32. The powder coating composition of claim 31where- 3,595,944 7/1971 Manmng 260 836 in: said dicarbox lic acidscontain 5 to 13 carbon atoms per mo1ecu1e y PAUL LIEBERMAN, PrimaryExaminer 33. The powder coating composition of claim 31 fur- 19 U therincluding: 6% to 35% by weight of a pigment.

26037 Ep, 41 c, 41 R, 830 R

